Wood can be used to construct almost any part of a home from the roofing and exterior walls to the floor and interior architectural elements as well as basic domestic items like furniture and cabinets. However, in recent years the cost of solid timber wood has increased dramatically as its supply shrinks due to the gradual depletion of old-growth and virgin forests. Indeed, it is particularly expensive to manufacture solid hardwood furniture and architectural features from such material because typically less than half of harvested timber wood is converted to natural solid wood lumber, the remainder being discarded as scrap.
Accordingly, because of both the cost of high-grade timber wood as well as a heightened emphasis on conserving natural resources, wood-based alternatives to natural solid wood lumber have been developed that make more efficient use of harvested wood and reduce the amount of wood discarded as scrap. Plywood, particle board and oriented strand board (“OSB”) are examples of wood-based composite alternatives to natural solid wood lumber that have replaced natural solid wood lumber in many structural applications in the last seventy-five years. These wood-based composites not only use the available supply of timber wood more efficiently, but they can also be formed from lower-grade wood species, and even from wood wastes.
These wood-based composite materials do offer a highly efficient way to use available wood material, however, because they typically consist of small particles (particle board), wood strands (OSB), flat pieces of low-grade wood species or some similar such material, products made from them do not have an attractive, grained appearance, but rather tend to have unsatisfactory aesthetic finishes. This may make them unsuitable for use in interior furnishings and for articles of furniture and cabinetry. Additionally wood-based composites can suffer when individual strands “pop up.” This makes the installation of surface covering materials, such as vinyl, hardwood flooring and ceramic tiles more difficult, and thus makes the use of wood-based of wood-based composite them unsuitable for use as floor materials.
Beyond the surface defects described above, there are still other difficulties presented by the surfaces of the wood-based composites. In particular, the wood-based composites tend to excrete wood extractives, which are found in the cambium or outer part of a tree that is adjacent to its bark. These extractives themselves tend to migrate from the wood-based composite into the floor or wall covering placed on top of the wood composite, causing staining in the covering. This problem with extractives especially problematic in the case of wood-based composites, because aspen and Southern yellow pine, two of the types of wood commonly used in wood-based composites, have particularly substantial amounts of extractives capable of migrating, and thereby staining floor covering materials.
One approach to addressing the aforementioned aesthetic problems is to prepare a special wood composite material by placing veneer layers upon the top and bottom surfaces of an internal, or “core” composite wood material. These veneer sheets are very thin, having a thickness of no greater than ⅛ inch, and are typically made from a decorative wood material, such as oak, birch, cherry and mahogany.
However, while these veneer-covered wood composite materials do have improved aesthetic finishes, they can be somewhat difficult to prepare and manufacture. In particular is a common problem referred to as “telegraphing”, where due to the thinness of the veneer layer, the texture of the underlying wood composite material presses through the veneer layer creating a non-uniform, uneven surface with numerous imperfections. Other surface defects like pitting, indentations, and voids have also been noticed as a result of applying a veneer.
Several solutions have been proposed to eliminate surface telegraphing. One technique is to use an intermediate layer between the core layer (especially an oriented strand board core layer) and the veneers such as is described in U.S. Pat. No. 5,506,026. This intermediate layer provides a smooth surface onto which the veneers may be laminated without surface telegraphing and indentations. While this technique is often effective it also creates a five-ply product that is considerably more expensive because of additional labor and material costs than a three-ply product. Other investigators, such as shown in U.S. Pat. No. 6,461,743 have considered using a combination of both an intermediate layer and additional control over the surface. But while this does adequately ameliorate surface telegraphing, it is even more time-intensive and costly than merely using an intermediate layer without further pretreatment.
Still another technique for preventing surface telegraphing is the application of a coating or putty to hide the texture or surface imperfections on the wood composite's surface, such as shown in U.S. Pat. No. 5,616,419. Unfortunately, this technique not only often fails to prevent telegraphing, it is also time consuming to distribute the glue across the surface of the wood composite material in sufficient concentration and evenness to ensure that the surface telegraphing will be absent.
Given the foregoing, there is a continuing need for an efficiently constructed wood composite material that has the excellent surface finish to be useful for applications where surface appearance is important such as interior domestic furnishings, furniture and cabinetry.